You shouldn't use contractions. You should actually start sentences with And/But despite what the above poster might have learned in elementary school. Justice Roberts does it all the time and done properly it can be quite useful.

Formal and polished English should comprise the content of your personal statement. Therefore, contractions are not acceptable, and furthermore, evidence a lack of professionalism. There are exceptions: for instance, if you are using a quote. However, veer far from using contractions.

Please contact me directly at info@writetrackadmissions.com, if you have any further questions about the personal statement, or the admissions process at large.

The personal statement is not meant to be a formal piece of writing - it's meant to shed light on your character. Avoiding contractions could affect the tone of your essay in an adverse way, depending on the topic at hand. If it is a light, or friendly topic, contraction use is perfectly okay. The goal is not to sound too serious. Don't use contractions in your resume/CV, however - Dani